1. Field of the Invention
The present invention relates to pipe lining techniques, and more particularly to a method of injecting resin into a pipe liner bag which is used to repair pipelines. The present invention also relates to a method of repairing pipelines using such a pipe liner bag which is applicable to repairing pipelines which may be steeply inclined with respect to the horizontal direction.
2. Description of the Related Art
When an underground pipe, such a pipeline or passageway, becomes defective or too old to perform properly, the pipe is often repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. Typically, the method is disclosed by Japanese Provisional Patent publication (Kokai) No. 60-242038.
According to the method described in the above-mentioned publication, the pipe repair method comprises inserting a sufficiently long tubular flexible liner bag into the pipe to be repaired by means of a pressurized fluid, like air and water. The tubular liner bag is made of a flexible resin-absorbent material impregnated with a thermosetting resin, and has the outer surface covered with an impermeable plastic film.
More particularly, according to the publication, the tubular flexible liner bag is closed at one end and open at the other; the tubular flexible liner bag is first flattened, then, the closed end of the tubular liner bag is tied to a control rope; the open end of the tubular liner bag is made to gape wide and hooked (anchored) at the end of the defective or old pipe in a manner such that the wide-opened end of the liner completely and fixedly covers and closes the pipe end; a portion of the liner is pushed into the pipe; then, the pressurized fluid is applied to the said portion of the tubular liner such that the fluid urges the tubular liner to enter the pipe. Since one end of the tubular liner is hooked at the end of the pipe, it remains there while the rest of the flexible liner bag is turned inside out as it proceeds deeper in the pipe. (Hereinafter, this manner of procedure shall be called "everting".) When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the control rope holds the closed end of the tubular liner bag to thereby control the length of the tubular liner in the pipe. Then, the everted tubular liner is pressed against the inner wall of the pipe by the said pressurized fluid, and the tubular flexible liner is hardened as the thermosetting resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag by means of a hot steam, etc. It is thus possible to line the inside wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
When the pipe liner bag for use in the above-mentioned pipeline repair method is impregnated with a resin, a method as shown in FIGS. 12 and 13 is conventionally employed. More specifically, a vacuum hose 108, connected to a vacuum pump (not shown), is first inserted into a pipe liner bag 101 from an end thereof. Then, from the other end of the pipe liner bag 101, a resin 105 is directly injected into the pipe liner bag 101 through a resin injecting hose 112, and thereafter the pipe liner bag 101 is evacuated by the vacuum hose 108, while an open liner 102 is everted and inserted by fluid pressure into the pipe liner bag 101 as shown in FIG. 13, thus impregnating the resin 105 into the pipe liner bag 101.
However, if the above-mentioned conventional method is applied to a pipe liner bag for repairing a steeply inclined pipeline, a bent portion of the pipe liner bag 101 presents an acute angle, which causes the resin to stay inside the pipe liner bag 101, and makes it difficult to evert and insert the open liner 102.
Also, since the installation of the open liner 102 takes a long time, a pot life of the resin 105 must be set long, which requires a long time for hardening of the resin 105, thus resulting in a longer work term.